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Hematology · Pathway

Thrombocytopenia: workup and management

Adults with a low platelet count: confirm it is real, see which action thresholds the count is under, read the pattern, rule out the emergencies (TTP, DIC, HIT, HELLP, anti-PF4 and other clotting causes), then see the ITP and platelet-transfusion rules that apply. Blank answers stay missing.

Action thresholds firstTTP · DIC · HIT · HELLP · anti-PF4ASH ITP 2026 updateAABB/ICTMG 2025Reviewed Oct 2026

1Platelet count

Enter 45 for 45,000/µL.

Is the low count real?EDTA can clump platelets in the tube (pseudothrombocytopenia).

2Pattern

Other blood counts

Time course

Setting

3Pregnancy

4Exposures and context tick all that apply, or none

5Red flags

Schistocytes on the smear

HemolysisReticulocytes over 2.5%, undetectable haptoglobin, or indirect bilirubin over 2 mg/dL (34.2 µmol/L)

New arterial or venous thrombosis

Bleeding

7Coagulation scores optional

ISTH overt DIC score (2001 algorithm). It applies only when an underlying disorder linked to DIC is present.

Underlying disorder linked to DICe.g. severe infection, cancer, trauma, obstetric complication

Fibrin-related marker (D-dimer or FDP), as graded by your lab

PT prolongation above the upper limit

Fibrinogen

8Transfusion or procedure question

How it works

Order of the answer

1. A count under 1 (including 0), a count over 1500, or one that looks typed per µL stops with a units check. 2. Two answers that contradict each other stop the page with “Check the answers”. 3. As soon as the count and “Is the low count real?” are answered: clumping stops with “not a true low count” (any bleeding, clot or hemolysis you marked is still flagged), and a count of 150 or more is not low. 4. Otherwise any unanswered required question is listed. 5. Then the full result: the threshold the count is under, emergency lines, pattern, workup, ITP steps if they apply, transfusion rules and follow-up.

The “Rule out first” box shows in every state. In the full result it lists only what your answers flag, plus one line naming the rest. Answers to questions that hide (trimester, HELLP labs, PLASMIC, SIC, cause for prophylaxis) are cleared, and cleared again when the question that opened them changes to a different answer.

One exclusion step decides which treatments may be named. A treatment it rules out never appears as advice; it appears only in the “Not advised”, “Deferred” or “Not covered” list with the reason. Thresholds are compared on the number exactly as typed (19.95 is under 20).

Action thresholds and the CTCAE grade

The headline names the lowest threshold the count is under: 10 (prophylaxis after chemotherapy or in consumption), 20 (lumbar puncture, low-risk IR, ITP admission), 30 (ITP treatment), 50 (major surgery, high-risk IR, severe bleeding), 100 (HELLP and preeclampsia; intracranial bleeding, UK) or 150. Each applies only in its own situation.

CTCAE v6.0 gradePlatelets ×10⁹/L
1below the lab’s lower limit, down to 75
2below 75, down to 50
3below 50, down to 10
4below 10

CTCAE is an oncology adverse-event grade, shown second. v6.0 (July 2025) moved the grade 3/4 boundary from 25 to 10.

Scores used

PLASMIC (1 point each): platelets under 30; hemolysis (reticulocytes over 2.5%, undetectable haptoglobin, or indirect bilirubin over 2 mg/dL); no active cancer in the past year; no solid-organ or stem-cell transplant; MCV under 90 fL; INR under 1.5; creatinine under 2.0 mg/dL. 0–4 low, 5 intermediate, 6–7 high. ISTH 2020 did not endorse a specific score and notes these scores were built in adults without pregnancy, cancer, sepsis or transplant.

ISTH overt DIC (2001, as reproduced in Blood 2022): only if an underlying disorder is present. Platelets over 100 = 0, 50–100 = 1, under 50 = 2; fibrin-related marker no increase = 0, moderate = 2, strong = 3; PT prolonged under 3 s = 0, 3–6 s = 1, over 6 s = 2; fibrinogen over 1.0 g/L = 0, under 1.0 = 1. 5 or more is compatible with overt DIC (repeat daily); under 5 suggests, but does not confirm, non-overt DIC. Exactly 100, 50, 3 s, 6 s and 1.0 g/L are scored in the higher band here (cautious reading). A 2025 ISTH revision exists but its primary text could not be verified.

SIC (sepsis): platelets 100 to under 150 = 1, under 100 = 2; PT-INR over 1.2 = 1, over 1.4 = 2; SOFA (4 items) 1 = 1, 2 or more = 2. SIC = total 4 or more, with platelets plus INR points above 2.

Not covered
  • Children and neonates (adults only).
  • Inherited thrombocytopenias and platelet function disorders.
  • Treatment protocols for TTP, complement-mediated HUS, other TMAs, DIC, APS, PNH and congenital TTP.
  • HIT management (use the HIT tool) and anticoagulant dosing when platelets are low.
  • Platelet refractoriness, product selection (HLA-matched, pathogen-reduced) and doses.
  • Splenectomy and the choice among second-line ITP drugs.
  • Dengue (AABB/ICTMG 2025 recommends against platelet transfusion without major bleeding).
  • Kidney failure and uremic platelet dysfunction (UK, BSH 2017: avoid platelet transfusion in renal failure, 1B).

Sources

  1. National Cancer Institute. Common Terminology Criteria for Adverse Events (CTCAE) v6.0, published 22 July 2025. Blood and lymphatic system disorders: Thrombocytopenia (grades 1–4). Shown only as an oncology adverse-event grade.
  2. Cattaneo M. Pseudothrombocytopenia and other conditions associated with spuriously low platelet counts. Haematologica 2025;110(8):1677–92. doi:10.3324/haematol.2024.286234
  3. Lardinois B, Favresse J, Chatelain B, Lippi G, Mullier F. Pseudothrombocytopenia—a review on causes, occurrence and clinical implications. J Clin Med 2021;10(4):594. doi:10.3390/jcm10040594
  4. American College of Obstetricians and Gynecologists. Practice Bulletin No. 207: Thrombocytopenia in pregnancy. Obstet Gynecol 2019;133(3):e181–93.
  5. American College of Obstetricians and Gynecologists. Practice Bulletin No. 222: Gestational hypertension and preeclampsia (interim update). Obstet Gynecol 2020;135(6). HELLP criteria and Box 3 severe features.
  6. Bauer ME, Arendt K, Beilin Y, et al. The Society for Obstetric Anesthesia and Perinatology interdisciplinary consensus statement on neuraxial procedures in obstetric patients with thrombocytopenia. Anesth Analg 2021;132(6):1531–44 (full text, PMC13109829: count 70 or more, Class IIa; 50–70 and under 50, Class IIb; concern for a hemostatic disorder or DIC, Class IIb; HELLP: recheck within 6 hours, Class IIb). doi:10.1213/ANE.0000000000005355
  7. Zheng XL, Vesely SK, Cataland SR, et al. ISTH guidelines for the diagnosis of thrombotic thrombocytopenic purpura. J Thromb Haemost 2020;18(10):2486–95 (Recommendations 1–3). doi:10.1111/jth.15006
  8. Zheng XL, Vesely SK, Cataland SR, et al. ISTH guidelines for treatment of thrombotic thrombocytopenic purpura. J Thromb Haemost 2020;18(10):2496–502. doi:10.1111/jth.15010 · Zheng XL, Al-Housni Z, et al. 2025 focused update of the 2020 ISTH guidelines for management of TTP. J Thromb Haemost 2025;23(11):3711–32 (no change to the iTTP recommendations). doi:10.1016/j.jtha.2025.06.002
  9. Zheng XL, Vesely SK, Cataland SR, et al. Good practice statements (GPS) for the clinical care of patients with thrombotic thrombocytopenic purpura. J Thromb Haemost 2020;18(10):2503–12 (Statements 2, 3, 8, 9, 13, 21, 27). doi:10.1111/jth.15009
  10. Bendapudi PK, Hurwitz S, Fry A, et al. Derivation and external validation of the PLASMIC score. Lancet Haematol 2017;4(4):e157–64. doi:10.1016/S2352-3026(17)30026-1. The original was not accessible this session; items, points and bands are as reproduced in Coppo P, Cuker A, George JN. Res Pract Thromb Haemost 2019;3(1):26–37, Table 1 (secondary). doi:10.1002/rth2.12160
  11. ISTH overt DIC score (Taylor FB Jr et al., Thromb Haemost 2001;86:1327–30) as reproduced in Popescu NI, et al. Disseminated intravascular coagulation and its immune mechanisms. Blood 2022;139(13):1973–86, Table 1 (reproduction, not the original; PMC8972096). doi:10.1182/blood.2020007208. A 2025 ISTH revision exists (Iba T et al. J Thromb Haemost 2025;23(7):2356–62, doi:10.1016/j.jtha.2025.03.038), but its primary text could not be verified and it is not used.
  12. Iba T, Di Nisio M, Levy JH, Kitamura N, Thachil J. New criteria for sepsis-induced coagulopathy (SIC) following the revised sepsis definition. BMJ Open 2017;7(9):e017046 (Table 3). doi:10.1136/bmjopen-2017-017046
  13. ISTH SSC communication. Disseminated intravascular coagulation and cirrhotic coagulopathy: overlap and differences. J Thromb Haemost 2024. doi:10.1016/j.jtha.2024.11.019 (title only used: the two overlap).
  14. Neunert C, Terrell DR, Arnold DM, et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Adv 2019;3(23):3829–66 (adult recommendations 1a–5; Table 2, the 2011 recommendations not re-addressed; Table 3 definitions). doi:10.1182/bloodadvances.2019000966
  15. Cuker A, Terrell DR, Sowdagar H, et al. American Society of Hematology 2026 guidelines for immune thrombocytopenia: initial and second-line therapy for adults with primary ITP. Blood Adv 2026;10(20):7076–97 (Recommendations 1, 2a, 2b). doi:10.1182/bloodadvances.2026021269 · ASH summary of changes (27 Aug 2026): 2019 recommendations 5–9 retired; 1a, 1b, 2a, 2b, 3 and 4 not re-addressed.
  16. Cines DB, Liebman H, Stasi R. Pathobiology of secondary immune thrombocytopenia. Semin Hematol 2009;46(1 Suppl 2):S2–14. doi:10.1053/j.seminhematol.2008.12.005 · Modi D, et al. Primary versus secondary ITP: 2023 McMaster ITP Summit. Thromb Haemost 2025;125(9):923–32 (hypogammaglobulinemia). doi:10.1055/a-2508-1112
  17. Metcalf RA, Nahirniak S, Guyatt G, et al. Platelet transfusion: 2025 AABB and ICTMG international clinical practice guidelines. JAMA 2025;334(7):606–17 (abstract only: strong recommendations carry high/moderate certainty, conditional ones low/very low; cited by population, not number). doi:10.1001/jama.2025.7529
  18. Estcourt LJ, Birchall J, Allard S, et al. Guidelines for the use of platelet transfusions (British Society for Haematology). Br J Haematol 2017;176(3):365–94. doi:10.1111/bjh.14423. UK guideline, labelled “UK (BSH 2017)” wherever used.
  19. Greenberg SM, Ziai WC, Cordonnier C, et al. 2022 Guideline for the management of patients with spontaneous intracerebral hemorrhage (AHA/ASA). Stroke 2022. Antiplatelet-related hemorrhage, patients taking aspirin: platelet transfusion with emergency neurosurgery (COR 2b, LOE C-LD) and without emergency surgery (COR 3: Harm, LOE B-R). Primary text not reached this session; wording from the emDocs summary (emdocs.net, “Intracerebral hemorrhage: 2022 guideline update”) — secondary.
  20. Garg A, Van Doren L, Dave E, Kohari K. The conundrum of thrombotic microangiopathy in pregnancy. BMJ Case Rep 2025;18(12):e266376. doi:10.1136/bcr-2025-266376 (case report with review — secondary).
  21. O’Shea RS, Davitkov P, Ko CW, et al. AGA clinical practice guideline on the management of coagulation disorders in patients with cirrhosis. Gastroenterology 2021;161(5):1615–27 (PICO 2A and 2B). doi:10.1053/j.gastro.2021.08.015
  22. Arnold DM, Nazi I, Warkentin TE, et al. Approach to the diagnosis and management of drug-induced immune thrombocytopenia. Transfus Med Rev 2013;27(3):137–45 (counts typically begin to recover within 1–2 days of stopping the drug). doi:10.1016/j.tmrv.2013.05.005 · Vayne C, et al. J Clin Med 2020;9(7):2212. doi:10.3390/jcm9072212
  23. US prescribing information (DailyMed): Zyvox (linezolid), Pfizer, Jun 2026 (setid 6e70e63b-bfd5-478d-a8ee-8ba22c9efabd), section 5.1; Depakote (divalproex), AbbVie, Apr 2026 (08a65cf4-7749-4ceb-6895-8f4805e2b01f), sections 2 and 5.8; CellCept (mycophenolate), Aug 2026 (37241e87-4af4-4dc3-a1aa-ea6f20d8dc40), section 1 (transplant only).
  24. Silczuk A, Habrat B. Alcohol-induced thrombocytopenia: current review. Alcohol 2020;86:9–16. doi:10.1016/j.alcohol.2020.02.166 · Silczuk A, et al. Alcohol Alcohol 2019;54(5):503–9 (platelets under 119 and complicated withdrawal). doi:10.1093/alcalc/agz061
  25. Serious Hazards of Transfusion (SHOT) Annual Report 2015, chapter 25: Post-transfusion purpura (definition: thrombocytopenia 5–12 days after cellular components with HPA antibodies).
  26. Lillo-Le Louët A, Boutouyrie P, Alhenc-Gelas M, et al. Diagnostic score for heparin-induced thrombocytopenia after cardiopulmonary bypass. J Thromb Haemost 2004;2(11):1882–8. doi:10.1111/j.1538-7836.2004.00949.x
  27. Schulman S, Arnold DM, Bradbury CA, et al. 2023 ISTH update of the 2022 ISTH guidelines for antithrombotic treatment in COVID-19 (VITT section: anti-PF4 immunoassays for diagnosing VITT, COR 1). J Thromb Haemost 2024;22(6):1779–97. doi:10.1016/j.jtha.2024.02.011
  28. Warkentin TE, Greinacher A. Platelet-activating anti-platelet factor 4 disorders. N Engl J Med 2026;395(5):478–91. doi:10.1056/NEJMra2502459 · Warkentin TE. Classification of platelet-activating anti-PF4 disorders (autoimmune and spontaneous HIT). Int J Lab Hematol 2025;48(2):259–71. doi:10.1111/ijlh.14486
  29. Antiphospholipid syndrome: the 2023 ACR/EULAR classification criteria include thrombocytopenia as a clinical domain and lupus anticoagulant, anticardiolipin and anti-β2-glycoprotein I as laboratory domains (Barbhaiya M, et al. Curr Rheumatol Rep 2025;27:41, doi:10.1007/s11926-025-01202-y; Alijotas-Reig J, et al. Autoimmun Rev 2025;25:103956, doi:10.1016/j.autrev.2025.103956). Catastrophic APS (secondary): Morecroft R, et al. Case Rep Rheumatol 2026, doi:10.1155/crrh/8852169. PNH (secondary reviews): Zhang T, et al. Expert Rev Clin Pharmacol 2026;19(6):499–508, doi:10.1080/17512433.2026.2677883; Raman G, et al. Transfusion 2026, doi:10.1111/trf.70379.
  30. US prescribing information (DailyMed): WinRho SDF, Kamada, Oct 2026 (setid fdb8ec91-f3ec-40c5-9337-23cc5bcc4c6e), boxed warning and sections 1.1, 2 (adults with chronic ITP; 8-hour monitoring; alternatives if hemoglobin under 8 g/dL); Rhophylac, CSL Behring, Aug 2025 (c1b5d801-336f-4541-a7d9-a8d4a110a4cc), boxed warning and section 1 (non-splenectomized adults with chronic ITP); Nplate (c45f9a58-37c1-4f76-8e36-97d38c577037), Promacta (7714a0ed-34bb-46e6-a0a5-b363908b22c2) and Doptelet (e2d5960d-6c18-46cc-86bd-089222b09852), section 1; Rituxan (b172773b-3905-4a1c-ad95-bab4b6126563), section 1 (no ITP indication).
  31. Acute fatty liver of pregnancy (secondary reviews): Rajput M et al. World J Nephrol 2025;14(4):110414, doi:10.5527/wjn.v14.i4.110414; Suzuki H et al. J Obstet Gynaecol Res 2025;51(2):e16230, doi:10.1111/jog.16230. ECMO (secondary, case-report background): AlFaifi M et al. J Med Case Rep 2026, doi:10.1186/s13256-026-06016-9.

Educational reference only — not a substitute for clinical judgment, institutional protocols, or specialist advice. Calculations run in your browser; nothing you enter is sent or stored.